Agro-physiological responses and anthocyanin levels of 'baligonhon' yam (Dioscorea alata L.) phenotypes subjected to water limiting environment

Sustaining crop productivity amidst climate change requires holistic approach to which crops and crop producers are at the center. Both the crops and the farmers should gain resilience with the effects of climate change to ascertain food security in the coming years. Hence, four studies were conducted in Lantapan, Bukidnon, Philippines to elucidate the effect of drought in yam (Dioscorea alata) and to unveil the cultural management practices employed by yam farmers during dry season cropping. 'Baligonhon' yam farmers in Bantuanon have variable sets of cultural management practices. Similarly, production volume and anthocyanin content differed across yam farmers. Use of heavier minisetts (100 g) as planting material, longer growth duration (approx 8 months) and installation of water impounding potentially favors yam production during dry season cropping. Occurrence of drought at 4 and 6 months after planting (MAP) greatly reduced yam yield by 28 and 48%, respectively. Plants subjected to drought stress at 2 MAP have recovered and produced similar yield levels with well-watered yam plants. Drought imposition at 4 and 6 MAP can lead to disturbed photosynthetic apparatus as manifested by reduced chlorophyll at these growth stages. Varying anthocyanin levels due to imposition of drought stress were observed, apparently on the tuber flesh color at harvest. Drought stress also reduced anthocyanin accumulation in purple yam phenotypes. However, anthocyanin levels were either reduced and increased in leaves and stems depending on the phenological occurrence of drought, suggesting active antioxidant activities under drought conditions. Based on the 9-point hedonic rating scale, the acceptability of tubers is reduced along with its fading color. However, results revealed that white yam phenotype is consistently acceptable even with simple preparation (boiling), suggesting higher potential for utilization as an alternative source of carbohydrates rather than discarded or left to rot in the farmers' fields.